Is any math can sort out date from time-milli? (eg:1544901911)
It is possible to get time by a initial modulus of 86400 and dividing 3600 (hour) and modulus by 3600 and dividing by 60 (minute) of overal milli.
Is it possible to get date from these, I really don't know how it works (just knows that it begined from 1970 Jan 1 onwards).
Not using any code language, I am just asking the mathematics behind this.
I have problems making sense of what you wrote. 86400 is the number of seconds in a day. So if you have the time in seconds, and want the time of the day, then modulo 86400 makes sense. As your question starts with time in milliseconds, modulo 86400000 would be more appropriate. But I guess we get the idea either way.
So as I said, extracting the time of the day works as you know the number of seconds in a day. The number of seconds in a year is harder, as you have to deal with leap days. You can have a look at existing standard library implementations, e.g. Python datetime. That starts by taking the time (or rather number of days, i.e. time divided by time per day, whatever the unit) modulo 400 years, since the number of whole days in 400 years is fixed. Then it goes on looking at 100 year cycles, 4 year cycles and years, with case distinctions for leap years, and tables containing information about month lengths, and so on. Yes, this can be done, but it's tedious plus already part of standard libraries for most languages.
I am developing a video gallery app in that I want to calculate the percentage of video watched.
For that I have a number of minutes of the video and total minutes watched by the user, if the user watched 10 minutes of a video twice I will save 20, and if the user watched the same video 3 times and at 3rd time he only watch for 4 minutes then I want to calculate the percentage watched for the last time.
I would like it be a like the method bellow, and I would need a formula for this.
function getPercentageWatched(videoTiming,totalMinWatched){}
If I understand you correctly, you are running the video in a loop. So if totalMinWatched ≥ videoTiming the user has seen the video at least once completely, and you are interested in the remaining percentage, i.e. the last portion that isn't complete.
If you compute totalMinWatched / videoTiming, that quotient will have an integer part (before the decimal point) indicating the number of completed runs, and a fractional part (after the decimal point) indicating the fraction of the last partial run. That fractional part times 100 is the fraction of the current loop iteration.
ratio = totalMinWatched / videoTiming
fraction = ratio - floor(ratio)
percentage = 100 * fraction
This can be a simple question, but I need to know.
How to set up oozie coordinator frequency at 1 minute frequency?
I need to run a shell script 1 minute interval.
Oozie Frequency representation,
frequency="${coord:minutes(1)}"
Update:
Cron Style representation,
frequency="0/1 * * * *"
With ISO8601, is there a way to specify a repeating interval which starts at a given time for any day, and repeats over time in that day?
For example, does the following hold:
R2/T09:00:00Z/PT1H = R/2000-01-01T09:00:00/P1D + R/2000-01-01T10:00:00/P1D?
Or is the former not correct under the standard?
The motivation behind this is to run a task at 9am and 10am every day.
No, Iso 8601 cannot irregular repetitions. You would need evaluate/run both of those expressions.
Cron expressions would be a better option as it is widely supported, especially for running tasks. You can find cron expression builders on the web and a library for every language (and OS support with crontab in Unix systems). This expression would handle your use case 0 0 9,10 ? * * * and would run at 9 and 10 am of every day of every year.
Sorry for the response 2 years later.
I'm running into a situation where a cron job I thought was running every 55 minutes is actually running at 55 minutes after the hour and at the top of the hour. Actually, it's not a cron job, but it's a PHP scheduling application that uses cron syntax.
When I ask this application to schedule a job every 55 minutes, it creates a crontab line like the following.
*/55 * * * *
This crontab line ends up not running a job every 55 minutes. Instead a job runs at 55 minutes after the hours, and at the top of the hour. I do not desire this. I've run this though a cron tester, and it verifies the undesired behavior is correct cron behavior.
This leads me to looking up what the / actually means. When I looked at the cron manual I learned the slash indicated "steps", but the manual itself is a little fuzzy on that that means
Step values can be used in conjunction with ranges. Following a range with "<number>" specifies skips of the number's value through the range. For example, "0-23/2" can be used in the hours field to specify command execution every other hour (the alternative in the V7 standard is "0,2,4,6,8,10,12,14,16,18,20,22"). Steps are also permitted after an asterisk, so if you want to say "every two hours", just use "*/2".
The manual's description ("specifies skips of the number's value through the range") is a little vague, and the "every two hours" example is a little misleading (which is probably what led to the bug in the application)
So, two questions:
How does the unix cron program use the "step" information (the number after a slash) to decide if it should skip running a job? (modular division? If so, on what? With what conditions deciding a "true" run, and which decisions not? Or is it something else?)
Is it possible to configure a unix cron job to run every "N" minutes?
Step values can be used in conjunction with ranges. Following a range
with "<number>" specifies skips of the number's value through the range. For
example, "0-23/2" can be used in the hours field to specify command
execution every other hour (the alternative in the V7 standard is
"0,2,4,6,8,10,12,14,16,18,20,22"). Steps are also permitted after an
asterisk, so if you want to say "every two hours", just use "*/2".
The "range" being referred to here is the range given before the /, which is a subrange of the range of times for the particular field. The first field specifies minutes within an hour, so */... specifies a range from 0 to 59. A first field of */55 specifies all minutes (within the range 0-55) that are multiples of 55 -- i.e., 0 and 55 minutes after each hour.
Similarly, 0-23/2 or */2 in the second (hours) field specifies all hours (within the range 0-23) that are multiples of 2.
If you specify a range starting other than at 0, the number (say N) after the / specifies every Nth minute/hour/etc starting at the lower bound of the range. For example, 3-23/7 in the second field means every 7th hour starting at 03:00 (03:00, 10:00, 17:00).
This works best when the interval you want happens to divide evenly into the next higher unit of time. For example, you can easily specify an event to occur every 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, or 30 minutes, or every 1, 2, 3, 4, 6, or 12 hours. (Thank the Babylonians for choosing time units with so many nice divisors.)
Unfortunately, cron has no concept of "every 55 minutes" within a time range longer than an hour.
If you want to run a job every 55 minutes (say, at 00:00, 00:55, 01:50, 02:45, etc.), you'll have to do it indirectly. One approach is to schedule a script to run every 5 minutes; the script then checks the current time, and does its work only once every 11 times it's called.
Or you can use multiple lines in your crontab file to run the same job at 00:00, 00:55, 01:50, etc. -- except that a day is not a multiple of 55 minutes. If you don't mind having a longer or shorter interval once a day, week, or month, you can write a program to generate a large crontab with as many entries as you need, all running the same command at a specified time.
I came across this website that is helpful with regard to cron jobs.
https://crontab.guru
And specific to your case with * /55
https://crontab.guru/#*/55_*_*_*_*
It helped to get a better understanding of the concept behind it.
There is another tool named at that should be considered. It can be used instead of cron to achieve what the topic starter wants. As far as I remember, it is pre-installed in OS X but it isn't bundled with some Linux distros like Debian (simply apt install at).
It runs a job at a specific time of day and that time can be calculated using a complex specification. In our case the following can be used:
You can also give times like now + count time-units, where the time-units can be minutes, hours, days, or weeks and you
can tell at to run the job today by suffixing the time with today and to run the job tomorrow by suffixing the time with tomorrow.
The script every2min.sh is executed every 2 minutes. It delays next execution every time the instance is running:
#!/bin/sh
at -f ./every2min.sh now + 2 minutes
echo "$(date +'%F %T') running..." >> /tmp/every2min.log
Which outputs
2019-06-27 14:14:23 running...
2019-06-27 14:16:00 running...
2019-06-27 14:18:00 running...
As at does not know about "seconds" unit, the execution time will be rounded to full minute after the first run. But for a given task (with 55 minutes range) it should not be a big problem.
There also might be security considerations
For both at and batch, commands are read from standard input or the file specified with the -f option and executed. The working directory, the environment (except for the variables BASH_VERSINFO, DISPLAY, EUID, GROUPS, SHELLOPTS, TERM, UID, and _) and the umask are retained from the time of invocation.
This is the easiest way to schedule something to be ran every X minutes I've seen so far.